1. Department of Earth and Space Science, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; 2. Guangdong Provincial Key Laboratory of High Precision Imaging Technology in Geophysics, Shenzhen, Guangdong 518055, China
Abstract：Because of the influence of air waves， the shallow water area is almost a blind spot for the commonly used marine controlled source electromagnetic detection method. However， due to the absorption and attenuation of seawater， the high-frequency components of magnetotelluric sounding signals are seriously attenuated in water areas. Therefore， both methods have shortcomings in terms of depth detection. To solve this problem， this paper proposes the marine auxiliary source broadband magnetotelluric method， which applies the controlled source audio magnetotelluric method to marine resource exploration and carries out electromagnetic data acquisition of mixed sources. In other words， the exciting source is deployed on the water surface in the far area， and the acquisition stations are deployed on the seabed to receive electromagnetic signals， so as to obtain the marine controlled source audio magnetotelluric data .By merging the two sets of data， broadband magnetotelluric detection in the whole sea area is realized. In addition， a three-layer geoelectric model including air， seawater， and seabed is derived， and each component of the electromagnetic field for the surface-excitation and seafloor-receiving acquisition is calculated to simulate and analyze the adaptability and feasibility of the marine controlled source audio magnetotelluric components. By simulating the broadband apparent magnetotelluric resistivity curves of different models and analyzing their characteristics， a more suitable electromagnetic detection method is proposed for marine resource exploration and deep geoscience research.
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